In a factory setting there are a multitude of mechanical and electrical components, each performing a particular function or functions as part of a system which may, for example, be an automated assembly line. While many of the systems components may be highly efficient, each will produce stray energy losses during its normal operation. For example, it is common for electromagnetic energy as well as mechanical/vibrational, thermal and acoustic energy to stray outside a motor stator into the surrounding environment. Similarly, fluid or air handling conduits and mechanical bearings produce stray mechanical energy typically in the form of mechanical oscillation.
Remote sensors located proximal to mechanical and electrical components may be used to determine the condition of those components or the surrounding system. In general, each of the remote sensors requires wiring for power and communication with a remote processor. However, such wiring dramatically increases the cost of each sensing device often making extensive remote sensing impractical. For example, it is not uncommon for the cost of such wiring to exceed the cost of the sensing device itself. Alternately, the remote sensing devices may be battery powered and provide information via an RF communications link. However, the batteries required to power each sensor add significant cost and maintenance problems, especially when the sensors are located in difficult to reach areas. Furthermore, batteries have an uncertain life and are therefore unreliable. They also suffer from low power density and rapid deterioration and aging especially in hostile environments. Also the load versus time curve for batteries typically show a very rapid decline in power output at the end of battery life following a relatively long period of fairly steady output. This makes it difficult to predict when batteries need to be changed.
Accordingly, there is a present need for an alternate method and apparatus for powering remote sensors which takes advantage of the stray energy radiated by the electrical and mechanical components of a system.